This project involving study of immunologic reactions in the pathogenesis of influenza pneumonia in syngeneic mice is ultimately aimed at providing a rationale for more efficient immunoprophylactic procedures against influenza. The models used will include adoptive or passive immunization of intact or irradiated mice with lymph node and spleen cells, subpopulations of these cells, or other materials from previously vaccinated donor mice, and intranasal challenge of the recipients with influenza. Control studies will utilize cells or other materials from unexposed donor mice and from donor mice vaccinated with an influenza serotype differing from the challenge virus. The effects of the transferred materials on the course of influenza pneumonia will be evaluated by following the histological course of the pneumonia in mice sacrificed at intervals, autopsy and culture of mice who die, and comparison of the survival curves for simultaneously challenged groups. Virus challenge studies will also be performed directly on mice immunized with differing influenza vaccines and appropriate control mice. Mechanisms by which the vaccines or transferred materials alter mortality with influenza pneumonia will also be sought using assays of serum and bronchial wash antibody, interferon, and in vitro responses of node, spleen and bronchial wash cells to virus antigen (proliferation, interferon release, migration inhibition, cytotoxicity).